In manufacturing electronic devices such as semiconductor devices, plasma etching may be performed to form an opening in an insulating film formed on a metal-containing conductive layer. When the plasma etching is performed, the insulating film is etched by plasma treatment with a gas containing fluorine. After the plasma etching is performed, a residue containing fluorine is generated on a surface of the conductive layer, which is exposed through the opening formed in the insulating film. If a target object is placed in an atmospheric environment after the plasma etching, the surface of the conductive layer is corroded. Since a hydrate is generated by reaction among a metal, fluorine and moisture in the air when the surface of the conductive layer is corroded, the corrosion of the surface of the conductive layer needs to be suppressed.
Japanese Patent Application Publication No. 2006-156486 discloses a technique for removing the residue on the surface of the conductive layer by plasma treatment with a gas containing nitrogen and hydrogen. However, it is difficult to completely remove the residue by the plasma treatment.
Japanese Patent Application Publication No. 2012-124351 discloses a technique for forming a silicon oxide film by a chemical vapor deposition (CVD) method to cover a surface of an insulating film and a surface of a conductive layer after the plasma etching is performed on the insulating film and before the target object is placed in an atmospheric environment.
Due to the presence of the silicon oxide film, even when the target object is placed in the atmospheric environment, the surface of the conductive layer and the residue are prevented from being in contact with the atmosphere. The silicon oxide film is removed in a subsequent step after the target object is placed in the atmospheric environment. The silicon oxide film is removed by wet etching. However, when the silicon oxide film is removed, the insulating film is partially considerably etched.
Therefore, after the insulating film is etched and before the target object is placed in the atmospheric environment, the surface of the insulating film and the surface of the conductive layer need to be covered with a barrier film. It is also necessary to suppress the partial etching of the insulating film when removing the barrier film, which is performed after the target object is placed in the atmospheric environment.